Devil In Disguise
by DeathByOTP
Summary: SPOILERS! for Supernatural Season 11 Dean finds Cas in the Bunker, but it's not really Cas. Just so it doesn't cause confusion anything between *these* is inside Cas' head and Dean can't hear it. Also when I say Cas I mean Cas being controlled by Lucifer unless it takes place inside Cas' head then it really is Cas. Sorry sounds confusing.
1. Chapter 1

Dean walked into the bunker after a food run. Sammy was out and Cas was nowhere to be seen. Dean took out the pie he just bought and slumped into the sofa.

'...love me tender, love me true, all my dreams fulfilled...' Dean's ears focused on the music, where the hell was it coming from? Dean figured the music would lead him to what Cas was up to so got to his feet and set off in search of Cas.

He walked to Cas' room first. No Cas. Then to the library. Nope still no Cas. The music seemed to be getting louder and louder till he ended up at some dingy little sitting room that in all honesty he had forgotten about. He could see Cas through the dimly lit room, he was sat on the small leather sofa seemingly lost in the music. Dean noticed a record player in the corner.

"Cas where did you find that thing?"

"It was just in here, it had a lot of vinyl too"

"So you're listening to Elvis?"

"He's a talented man Dean"

"Not denying that Cas"

"He's handsome too" Dean huffed a little at Cas' remark.

"I guess if you're into that kind of thing" Dean mumbled. Cas stood up and stalked closer to Dean till they were practically chest to chest.

"What's wrong Dean, are you jealous?"

"Hell no. You can crush on anyone you want l don't care" Dean's voice same out sounding sulky.

"You are so jealous Dean, don't worry I think you're handsome. Well actually I think you're, well..." Cas leaned forward till his lips were right next to Dean's ear "really hot" Dean was taken aback, Cas was never so forward, he could feel his cheeks burning slightly.

**A voice spoke up in Cas' head "Lucifer I swear, leave Dean out of this. You are supposed to be using my vessel to defeat the darkness, not for this."

"Calm down Castiel" Lucifer spoke in a mocking tone, "I'm just helping you out, you really should be thanking me."

"What goes on between me and Dean is none of your business, just do your job and back off" Castiel snarled.

"Oh dear Cassie, you really shouldn't talk to me like that. I am doing you a favour, you wouldn't have the guts to tell Dean how you feel so I am going to do it for you, Okay?"

"Lucifer please don't do this"

"Sorry, I can't talk now I'm too busy" Lucifer sang before blocking Cas' voice out again.**

"Cas are you okay?"

"Never better Dean" Cas' hand reached out and he stroked a finger along Dean's smooth bottom lip, his other hand rested on Dean's shoulder. "You still don't see it do you Dean? How obvious do I need to be?"

"What are you talking about Cas?" He glanced at the hunter, his face was full of confusion.

"For the love of...just come here" Cas grabbed the back of Dean's neck gently but firmly and guided him closer. Dean didn't pull away, he dropped his gaze to Cas' lips, his heart was thumping in his chest, his palms started to sweat. He could feel Cas' breath ghosting across his nose as he spoke, he was sure that this was some kind of weird dream, it wouldn't be the first dream about Cas that was sorta like this. He tried to figure out what was going on but Cas' lips were on his and he abandoned any thought. Fingers dancing over his hip bones, his own hands working their way into Cas' dishevelled hair, he felt Cas nip at his bottom lip. The angel's mouth worked it's way along Dean's jaw line to his ear and his teeth lightly grazed his earlobe, Dean shivered and dug his fingers into Cas' slender back to pull him even closer. His mouth kept moving, leaving a burning trail wherever it touched, resting on the pulse point in Dean's neck he bit down. Dean groaned, there was no space left between their bodies, Dean could feel every movement Cas made.

There was a flicker of the lights and the record player suddenly seemed to get louder 'You look like an angel, walk like an angel, talk like an angel but I got wise. You're the devil in disguise..." Lucifer knew Castiel had done that, he was going to pay.

**"I thought I told you not to interfere" Lucifer chastised Cas. "We are just getting to the good part, don't interrupt, it's rude"

"He's not stupid Lucifer, he will figure out that it is you"

"He's not doing well so far huh? Maybe your precious Deanie isn't as smart as you think."**

"That was weird, did you do that Cas?"

"It could've just been an energy spike caused by my grace, probably because I'm so excited" Lucifer did his best to sound like Cas, he didn't want Dean to realise that he wasn't Cas, he wanted to have some fun with this if for no other reason than to mess with Cas for that stupid little stunt.

"That makes sense I guess" Dean was suddenly a little suspicious, maybe this was a dream after all. Cas hooked his fingers under Dean's t-shirt and pulled it off, his fingers then worked swiftly unbuttoning his own shirt and it was thrown to the side with Dean's.

Lips worked their way down Dean's chest, tongue occasionally licking tiny trails, "Do you want me Dean? It's that simple, all you need to do is say yes" Dean stared down intending to look into Cas' bright blue eyes but instead was met with dull eyes. Dean stumbled back nearly tripping in the process, it all made sense now. The flirtatiousness, the record player getting louder on that particular song, the 'say yes' and of course the hand on the wrong shoulder.

"You're not Cas"

"Well done Dean, took you long enough" Lucifer's grin split across Cas' face.

"What have you done to him Lucifer, if you've hurt him I swear I'll kill you myself"

"C'mon Dean you don't need him, I'm here now" He reached out to touch Dean again and Dean backed away.

"Don't touch me you goddam twisted freak" Dean roared at him.

"You weren't complaining before"

"Cause I didn't know it was the freaking devil! Where is Cas? What did you do?"

"I didn't do anything Dean, Cas willingly gave his vessel to me, he did it to save yours and Sammy's sorry asses."

"Why would he do that?" Dean was trying desperately to hold back tears, he was no way about to start blubbering in front of Satan.

"Because he wanted to protect you, how sweet, plus he was so broken down 'cause he thought you didn't care about him. It's tragic really."

"He knows I care about him, I'll get him back and I'll send you back to your damn cage. We don't need you to fight the darkness, hell no one needs you for anything."

"Aww Dean, you're so cute when you're defensive."

"Shut your damn mouth" Dean's voice softened, "Cas if you're in there I'm sorry, I do care about you, I'll get you back. Hang on please Cas, I love you."


	2. Chapter 2

Sadly there is a lot of little bits I have to clarify so yeah sorry.

-Lucifer is still living in the bunker because Dean doesn't want to kick him out because he wants to keep an eye on him and because obviously he wants to keep Cas around so he has Lucifer in the bunker but is guarding any places that would be dangerous for Luci to get to.

-Same applies as last chapter anything between **these** is in Cas' head so only Cas and Lucifer can hear it.

-Cas can see, hear and feel everything.

-This may sound stupid but it is relevant I swear, Dean is wearing jeans and a t-shirt with his robe open over the top.

-If I say Lucifer he is still in Cas' vessel but I don't want to confuse things by calling Lucifer, Cas. I did refer to Lucifer as Cas in the first chapter but that is because Dean didn't know he wasn't Cas

-Sam doesn't yet know about Lucifer, he is away and Dean hasn't been able to get in contact with him but he could return at any time.

-The potion has the consistency of a paste.

Hope that all makes sense.

A loud thud echoed through the bunker's library, a disoriented Dean's head whipped up and he grabbed his pistol. He scanned the library for signs of trouble but instead he found books scattered on the floor around the desk. He must have fallen to sleep looking for banishment spells. Truth is he had been racking his brain since he found out about Lucifer, he needed to get rid of that great big bag of dicks and get Cas back. So far though he was having no luck, oddly enough there weren't really any spells for kicking an archangel out of a meatsuit without disrupting another angel sharing the same vessel. Dean wasn't about to give up though, he just needed some coffee to perk him back up. Dean exited the library pausing briefly to lock it behind him. He passed through the main living room on the way to the kitchen, Lucifer was sprawled across the couch. Head tipped back humming to himself, Dean took a mental note that he had his shoes on the couch too. If Sam was here he would freak, he always bitched at Dean for it and he was starting to see why, what a rude douchebag.

"Hey Deano getting any further to saving your precious angel yet?" Dean's fingers grazed over his gun, god he wished it wasn't Cas' body he was using or he would put a bullet between his eyes just for the hell of it. "What's wrong, don't want to talk to me Princess?"

"Keep laughing bitch, but I killed Death, I fought the mark of Cain and stopped the apocalypse so I can sure as hell find a way to put you back in your damn box."

Lucifer pouted "C'mon baby why so tense, would you like me to give you a massage?" He winked at Dean and Dean let out a low warning growl.

"You touch me again and I'll tie you up, the only reason you're not chained and tortured already is I don't wanna hurt Cas' meatsuit."

"Aww Dean, I'm sure your boyfriend wouldn't be opposed to a bit of kink."

Dean opened his mouth to make some smart ass remark back but his brain went blank. "Screw you Lucifer and get your damn feet off the couch" Dean slapped his feet down as he walked past to the kitchen. As soon as he was in the kitchen he slammed the door and sunk to his knees, he knew he was being soft on Lucifer and he hated himself for it but he couldn't bring himself to hurt Cas.

This could actually work, Dean rubbed his eyes with disbelief, he had actually found something that could work. It was a long shot but he was willing to try anything. He threw open the library door, quickly locked it and sprinted to the bunkers storage room. He sifted through bottles, packets and god knows on his hunt for the ingredients for the spell. The spell if it worked should give the original host of the vessel control over it, Dean hoped he could give Cas enough control so he could keep Lucifer at bay while they tried to think of something to get rid of him totally. Dean shoved a small vial of kelpie blood into his robe, followed closely by two pots, one of calamus root and one of asafetida. Now he just needed something that belonged to the person before they were possessed, he knew exactly what he could use.

Dean was back on his way to the kitchen, he dropped off the ingredients in the library and locked them in just to be safe, he couldn't let Lucifer know he was onto something or risk him screwing with it.

"Paying me another visit huh? " Lucifer chimed, his gaze never lifted from the magazine he was reading, "You just can't resist me can you?".

"Burn in hell" Dean threw a short insult back, he was too preoccupied with wanting to check that what he was looking for was still in the kitchen.

"Dean that was so mean I think I might cry" Lucifer started to fake sob and clutched his heart. But Dean didn't see, he was past him and in the kitchen.

He started rifling through cupboards, he was sure it was still in here somewhere, Sammy had a habit of rearranging the general kitchen area but he knew he wouldn't have thrown it away. Hands frantically scrambled through pots and tins and jars until he finally saw it. It sat there, practically glowing, a tiny jar of honey. Dean picked up the tiny jar and clutched it, he fought back a couple of tears. He remembered when Cas was obsessed with bees, it was the honey that Cas made for him all that time ago, Cas always considered Dean and remembering that made Dean feel even guiltier.

The ingredients were mixed, now for the hard part, he had to find a way to smear some across Lucifer's heart. What kind of damn idiot made a spell where you had to half undress the other person to do it? He could just try running in there and ripping the shirt open and smearing it on but he didn't see that ending well for him, he could only think of one other way and he really didn't want to do it but he was out of other options. He scraped some of the potion into the small glass vial and slipped it into his gown pocket before leaving the library, locking it and hiding the keys. He padded into the living room, Lucifer was leaning back over the couch arm in a very childish fashion.

"Have you come to play with me now Dean? I'm getting bored." Lucifer whined.

"No I've come to talk"

"You actually want to talk to me now?"

"I want to get Cas back"

"Sorry Dean, ain't gonna happen yet"

"Lucifer please, I just, I need to tell him how much I want him. I can give him anything he wants, I'll treat him better I swear"

"He wants you Dean, you wouldn't believe some of the thoughts he has about you, I mean I thought angels were supposed to be all innocent but you've done a real number on him"

"What thoughts?"

"I can't tell you Dean, I'd have to show you"

Dean knew this was his chance and he had to take it, "Then show me"

**"Aww look Cas he's given in, looks like I get to have some real fun with your hunter now"

"Dean wouldn't, there's no way he would have any interest in you Lucifer"

"Looks like you're wrong, see?" Cas could see Dean getting up and walking to Lucifer, he saw Dean reach out and touch his face, he heard Dean speak.

"I thought you were supposed to be showing me something?" Dean's voice came out husky as he continued to caress his vessel's face, neck and chest. Cas couldn't quite believe what he was seeing.

"Dean no..." Cas whispered.

"See, Dean wanted to get a piece of your vessel, he didn't want you Castiel, he hasn't even see the real you"

"That's not true, it can't be"

"Don't worry Cassie, I'll let you watch. I bet I can even make him beg, I've seen your fantasies, I know you'd love to make him beg. Shame though he is gonna be begging me**

"This is a little suspicious Dean, I mean you had no interest at all earlier, why now?" Lucifer didn't really care why Dean had changed his mind, he only wanted any of this to mess with Castiel and this was too good of an opportunity to let it pass.

"Cause I've realised you're the closest thing I can get to Cas now he's gone" Dean had to bite back bile, that was such a damn lie, it actually made him feel sick. He wouldn't take anyone over Cas and he wouldn't give up on him, he hoped Cas knew that if he could see any of this.

"Hmm I'm not convinced Dean, really all you're saying is you can't bang the angel you want so you'll make do with me, it's kind of insulting"

"Fine you got me, I want you now because I wasn't willing to admit earlier that sex with an archangel must be damn awesome" Dean hoped Lucifer didn't detect the hint of sarcasm in his voice that he just couldn't seem to hide.

"Maybe I'm not interested in getting it on with one of my Daddy's little projects" His voice was laced with bitterness, "So you'll have to convince me, show me something good that you humans can do"

"Like what?"

"Beg me" Dean's eyes widened in shock, this guy was taking the piss, his pride was about to take a massive hit but he hoped it'd be worth it for Cas.

"Please"

"That's pathetic, you can do better, get on your knees"

Dean gritted his teeth but lowered to his knees "Please Lucifer, I want you"

"You want me to what?" A huge shit eating grin spread across Lucifer's face as he stared down at Dean.

"I want you to show me how good an archangel can be"

"That'll do I suppose" His hands were fisted into Dean's shirt as he ragged the Winchester to his feet so they were just about face to face. Lucifer stuck out his tongue and traced along Dean's bottom lip. Dean's lips tasted sickly sweet but with a bitter tinge, Lucifer didn't notice but Cas knew exactly what it was. Hands were roaming along the waistband of Dean's pants, Dean felt fingers working the button and the zip. "What's wrong Dean? You don't seem too into this and I thought you would be after all that begging".

"Sorry I was just distracted by what you were doing" Dean was lying through his teeth, he hoped Lucifer didn't pick up on it, he didn't want all this to be for nothing.

"Well get involved Winchester or I might just stop". Dean reluctantly reached out and wrapped an arm around Lucifer's waist. Lucifer pushed closer to Dean trapping his own hand between them which was still playing with the opening on Dean's pants, he stretched his fingers slightly and started to pull down the boxers.

"Wait"

"Dean I'm getting sick of all these interruptions, anyone would think you don't want this"

"No I was just about to say Sammy could be back at any time, we should really go to a bedroom"

"I don't care if Sam sees"

"No but he will figure out you're not Cas, he knows Cas is shy so he wouldn't do this out in the living room"

Lucifer paused for a moment, Dean was right, he didn't want Sammy to find out he was back just yet, plus how much fun could he have teasing Sammy about banging his big brother at some point. "Okay let's go then"

Dean walked a few steps behind Lucifer, he silently dipped his finger into the small vial and scooped as much potion onto his finger as he could. He quickly dumped it onto his tongue, it tasted like honey with copper mixed in, he silently thanked god that it didn't taste worse.

"In this room" Lucifer opened a bedroom door, it was a plain room, it was just a spare. Dean nodded and followed Lucifer inside. Dean had barely been inside the room for a second and he was slammed back against the door, Lucifer's hand dipped inside Dean's pants again fumbling around with the material of his underwear, he managed to shift the underwear down slightly and fingers dragged lightly over bare skin. Dean tried his hardest not to get distracted as he felt a strong hand wrap around him, he played along making little throaty moans for a while then he started to unbutton Lucifer's shirt, Lucifer made a grunt of approval as Dean dragged his nails down the newly exposed flesh before leaning forward and pressing small kissed along his neck and down to his chest. Dean glanced up quickly at Lucifer, before poking out his tongue and licking a stripe over his heart. Whatever survived of the paste was smeared across his chest, Dean whispered the incantation and there was a sudden flash of blue light.

"Dean?" The voice sounded like Cas. Dean felt a hand being swiftly removed from his underwear.

"Cas? Is that you? Did it work?"

"Yes Dean it's me, thank you for rescuing me"

"Cas I'm so sorry, you didn't need to feel unwanted, I'll always want you and I know I suck at showing it but I love you Cas"

"Oh Dean, I love you too" Dean felt arms wrap around his chest, a warmth flooded through his heart.

"I'm gonna look after you forever baby, no one will take you away from me again"

"So Dean..." A blush spread across his face "Shall we continue where we left off?"

"God yes... I mean Hell yes... Damn it just yeah Cas kiss me" Dean was kissed with such ferocity that he stumbled, an arm caught him around the waist and heaved him forward sending their bodies crashing together, both men were shirtless now and as they stumbled towards the bed they lost more and more clothing until they were down to their boxers. Dean was being straddled by the angel who was rolling his hips slightly eliciting small gasps from the hunter.

"Dean?"

"Yeah Cas?"

"Would you do something for me? I mean it's something I really want to try" A blush crept across his cheeks. "I don't know how to ask though"

"Just tell me Cas and I'll do it"

"Can i show you? Then we can try it?" Dean nodded as the angel crawled down his body till his mouth was level with Dean's boxers. His mouth pressed to the fabric making it warm and wet against Dean. Dean moaned as he felt slight nibbling, he had no idea where the angel even learnt this stuff but he wasn't half bad at it. "I'm too nervous to do any more, do you think you could try it for me?"

Dean didn't need to be asked twice he pushed the angel back onto the bed and pulled the boxers down his narrow hips. Dean dipped his head forward to meet the now bare flesh, he ran his tongue experimentally before deciding to go further. The angel tugged at Dean's short hair and moved his hips in time with his mouth.

Fingers released Dean's hair, "Dean, I want you"

He looked up, "I want you too Cas"

"Can I have you?"

"You mean like?" Dean gave Cas a knowing look.

"Intercourse, yes Dean" Dean smiled, how blunt Cas was never failed to amuse him. "So can i?"

"Yeah Cas, just be careful okay? I'm new to this too"

"Of course Dean".

After some preparation, which Dean had to admit was pretty hot and a little painful, they were finally ready. The angel leaned over Dean, bodies resting together as they exchanged a fiery kiss.

"Ready?"

"Cas?"

"Yes Dean?"

"I'm glad I have you back"

Dean watched as a dark grin spread across Cas' usually serene face, "Wow you humans are even stupider than I thought" Dean heard the voice, it wasn't Cas. Dean instantly reacted and shoved as hard as he could and sprinted to the door, grabbing his robe on the way.

"You sick bastard, what did you do? He was back I got him back with the spell"

"No Dean you didn't, please you really think that stupid little spell would work on me? I'm an archangel not some weak little demon that you can banish, I just thought I'd have some fun with you. By the way you're really good with your mouth, bet it's not the first time you've done that. Did you and Sammy used to practise on each other?"

"I'm gonna kill you, I'll make sure you never come back from wherever the hell I send you to"

"Yawn, this is getting tiring Dean, you can't do anything to get Cas back, well no actually that's a bit of a lie. There is one thing you can do"

"What is it? I'll do anything"

"Say yes to me, give me your vessel instead, your vessel is stronger than this one"

"You want my body?"

"Well I could've had that about 2 minutes ago, but yeah I do want your body just in a different way"

"You swear Cas will be fine?"

"You have my word"

"Then yes, you hear me you sick twisted son of a bitch? YES"

A flash of light filled the bedroom and Cas screamed "DEAN DON'T DO IT"

"Aww Hello Cassie, nice to see you again" Dean's face twisted into Lucifer's sick smirk. "Your boyfriend did this to save you and now I have a stronger vessel, plus this'll really piss Michael off, he couldn't get the Righteous man to say yes to him but I could"

"Your crazy Lucifer, Dean fought off the mark of Cain, he can fight you too" Cas' voice was deep and gravelly.

"HELLO? DEAN? ARE YOU HOME? CAS?" Lucifer's eyes widened, Sammy was home.

"I'm in here Sammy, Cas is in here too" Lucifer shouted back in his best Dean impression. Cas opened his mouth to speak and with a wave of his hand Lucifer had silenced him, he tried harder to shout but he just couldn't.

Sam popped his head around the door "Woah Dean, I don't want to see what you guys have been upto" Sam half covered his eyes upon seeing Cas was still stark naked and Dean was wearing a mostly open robe. Cas started to redress himself.

"Why not Sammy? Are you jealous?"

"Dean that's sick. I just don't need to see you guys naked is all"

"That's a shame Sammy, I'd like to see you naked"

"Dean what's with you?"

"Guess again Sammy, I'm not Dean" Sam staggered backwards like he had been punched in the gut.

"No it can't be you, your in the cage..."Sam stammered trying to make sense of any of this.

"Good old Cassie let me out, why don't you tell him Cas?" With a wave of his hand Cas could speak.

"Sam I'm sorry he told me he could defeat the Darkness so I said yes then Dean said yes so he could save me"

"You missed out the best part, ya know the foreplay" Cas glared at Lucifer. Sam stared at Dean's face before falling sideways and throwing up, it was like his worst nightmare had come true, Lucifer was bad enough in the cage, what was he gonna be like let loose on Earth? Cas was at Sam's side instantly holding him up. "Castiel you should make up your mind about which brother you want honestly."

"You know how I feel about Dean" Cas snarled at him.

"Good cause truth be told Castiel, I want Sammy for myself"

Sam regained some composure and rose to his feet, he squared up to Lucifer, "Didn't I make myself clear in the cage? I am not ready to be your bitch."

"We will see about that won't we Sammy?" Lucifer leant into Sam so their noses were almost touching, Sam didn't back away, he didn't want to seem scared, "The angel over there and your big brother, the mighty righteous man have been my bitches, make no mistake your time will come too"

"Over my dead body, I will save Dean, gank Amara and send you back to your cage myself if I have to"

"You won't have to do it alone Sam, I am with you" Cas clapped a hand onto Sam's back to reassure him.

"Oh I'm really scared of the reject angel and the one Winchester that's left"

Sam spoke with a newfound confidence, "You should be Lucifer, you won't win"


End file.
